SPRINGFIELD – Northeast Utilities’ $718 million plan to upgrade 39 miles of high-voltage power lines from Ludlow to Bloomfield, Conn., is just about halfway done, helped along by a mild winter, and set to be completed in late 2013.

The reliability project also has created 350 direct construction jobs and helped to support or create a total of 1,400 jobs in construction, design, government oversight, health care, food service and accommodations, real estate and retail, said Frank J. Poirot, senior communications specialist with the utility.

Workers at the job site include operating engineers running the cranes and heavy equipment, electricians and carpenters. Most of those workers are local and members of local construction trades unions, Poirot said.

But the general contractor on the project is PAR Electric of Kansas City, Mo. PAR Electric is pretty much the only contractor in the country capable of such a job, Poirot said this week.

“You just don’t find people who can work on 345,000-volt line,” he said.

The project is meant to unclog a bottleneck in the region’s electric grid identified by ISO New England and is funded by charges to power bills across New England. It is one of four projects collectively called the “New England East-West Solution.” The other three projects are in central Massachusetts, eastern Connecticut and Rhode Island and are not scheduled to begin until 2013.

Workers are replacing the relatively low-capacity 115-kilovolt copper lines with 345-kilovolt steel and aluminum lines during the three-year project.

Contractors also are upgrading electrical substations, including the Agawam Substation on Springfield Street and Ludlow Substation. They are also building two new switching stations: Cadwell Switching Station in Springfield and Fairmont Switching Station in Chicopee. There will be upgrades at Shawinigan Switching Station in Chicopee and South Agawam Switching Station in Agawam.